Loranger Jessy, Blonder Benjamin, Garnier Éric, Shipley Bill, Vile Denis, Violle Cyrille
CNRS, Centre d'Écologie Fonctionnelle et Évolutive (UMR 5175), 1919 route de Mende 34293 Montpellier Cedex 5, France Université de Sherbrooke, 2500 blv. de l'Université, Sherbrooke J1K 2R1, Canada.
Environmental Change Institute, School of Geography and the Environment, University of Oxford, Oxford, UK.
Am J Bot. 2016 Jun;103(6):1050-60. doi: 10.3732/ajb.1500483. Epub 2016 Jun 15.
Secondary succession is a worldwide phenomenon affecting plant communities. Studying functional variation during succession aids in understanding the mechanisms through which environmental shifts drive succession. We investigated changes in the functional space occupied by herbaceous communities during succession. Furthermore, since different traits are differently affected by environmental conditions, we asked how considering different sets of plant traits impacts those changes.
Using a chronosequence of Mediterranean old fields (2-42 yr after abandonment), we analyzed shifts of the occupied functional space during succession, how the volume of occupied functional space varies compared with null expectations, and the functional overlap between communities of different successional status. We repeated these analyses considering (1) the leaf-height-seed functional dimensions separately and together and (2) different sets of traits representing those dimensions.
From early to late succession, a shift toward nutrient conservative-light competitive species occurred. Functional strategies of mid-successional communities appeared more diverse than expected by chance and less diverse than expected for early and late communities. Early and middle stages overlapped the most. These patterns were generally robust to the choice of functional axes, though important trait-specific exceptions occurred.
We showed evidence for a well-defined history of successive dominance of different assembly mechanisms along succession, resulting in a generally stronger functional diversification in mid-succession. We also demonstrated that different traits typically grouped under one functional dimension can substantially affect the results, discouraging the use of surrogate traits from the same dimension.
次生演替是影响植物群落的一种全球现象。研究演替过程中的功能变化有助于理解环境变化驱动演替的机制。我们调查了草本群落演替过程中所占据的功能空间的变化。此外，由于不同性状受环境条件的影响不同，我们探讨了考虑不同的植物性状集如何影响这些变化。
利用地中海弃耕地的时间序列（弃耕后2 - 42年），我们分析了演替过程中所占据功能空间的变化、所占据功能空间的体积与零期望相比如何变化，以及不同演替状态群落之间的功能重叠。我们分别和综合考虑（1）叶 - 高 - 种子功能维度，以及（2）代表这些维度的不同性状集，重复这些分析。
从演替早期到晚期，出现了向养分保守 - 喜光竞争物种的转变。演替中期群落的功能策略似乎比随机预期的更多样化，比早期和晚期群落的预期多样化程度更低。早期和中期阶段的重叠最多。这些模式通常对功能轴的选择具有稳健性，尽管存在重要的性状特异性例外情况。
我们证明了不同组装机制在演替过程中连续主导的明确历史证据，导致在演替中期通常有更强的功能多样化。我们还证明，通常归为一个功能维度下的不同性状会显著影响结果，不鼓励使用来自同一维度的替代性状。
